regmap: Make reg_config reg_defaults const

The reg_defaults field usually points to a static per driver array, which should
not be modified. Make requirement this explicit by making reg_defaults const.
To allow this the regcache_init code needs some minor changes. Previoulsy the
reg_config was not available in regcache_init and regmap->reg_defaults was used
to pass the default register set to regcache_init. Now that the reg_config is
available we can work on it directly.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

drivers/base/regmap/regcache.c

@@ -108,7 +108,6 @@ int regcache_init(struct regmap *map, const struct regmap_config *config)
 		return -EINVAL;
 	}
 
-	map->reg_defaults = config->reg_defaults;
 	map->num_reg_defaults = config->num_reg_defaults;
 	map->num_reg_defaults_raw = config->num_reg_defaults_raw;
 	map->reg_defaults_raw = config->reg_defaults_raw;
@@ -127,10 +126,10 @@ int regcache_init(struct regmap *map, const struct regmap_config *config)
 	 * won't vanish from under us.  We'll need to make
 	 * a copy of it.
 	 */
-	if (map->reg_defaults) {
+	if (config->reg_defaults) {
 		if (!map->num_reg_defaults)
 			return -EINVAL;
-		tmp_buf = kmemdup(map->reg_defaults, map->num_reg_defaults *
+		tmp_buf = kmemdup(config->reg_defaults, map->num_reg_defaults *
 				  sizeof(struct reg_default), GFP_KERNEL);
 		if (!tmp_buf)
 			return -ENOMEM;

include/linux/regmap.h

@@ -83,7 +83,7 @@ struct regmap_config {
 	bool (*precious_reg)(struct device *dev, unsigned int reg);
 
 	unsigned int max_register;
-	struct reg_default *reg_defaults;
+	const struct reg_default *reg_defaults;
 	unsigned int num_reg_defaults;
 	enum regcache_type cache_type;
 	const void *reg_defaults_raw;